This invention generally relates to railroad car door operating systems, and more particularly relates to a method and apparatus for preventing the unauthorized operation of such car doors.
The present invention has particular utility when used in connection with railroad hopper cars equipped with bottom unloading features. In order to remove the labor involved in manually opening and closing the doors of a hopper-type railroad car, resort has been had to pneumatic-controlled apparatus for automatically opening and closing such doors in response to an externally generated command. A convenient source of power for these pneumatic devices is an auxiliary train line which couples air pressure from the locomotive engine in seriatim to each car in the train. Each railroad car is conventionally provided with a reservoir tank which is tapped into the auxiliary train line, for supplying air pressure to the pneumatic apparatus of that car, and to act as a buffer to reduce fluctuations in the auxiliary train line air pressure.
To further automate the procedure for quickly and automatically operating the hopper doors, the railroad car is in many cases provided with an electrical system which includes a pair of pick-up shoes on diagonally opposing corners of the car which contact wayside electrical rails. Engagement within the wayside rails will activate solenoids to operate a pneumatic directional control valve to either open or close the hopper car doors, depending on the polarity of the electrical source. For versatility, and sometimes by reason of necessity, the pneumatic directional control valve can also be manually actuated by push buttons.
To provide as secure a system as possible, these manual push buttons are enclosed in a lock box to prevent unauthorized operation, such as by vandals. It can be appreciated that an inordinate amount of labor and expense is involved when vandals break into the lock box, operate the push button and dump the load on the railroad tracks. By and large, the only way to clean up the cargo is by time consuming hand labor. Through experience it has been found that the unauthorized dumping of a hopper car seldom occurs when such cars of a train are connected to the locomotive. This is generally the case because the locomotive is continuously moving the cars on the track, or about a freight yard.
Vandalism frequently occurs, however, when a car or a connected string of cars are left unattended to be later moved and dumped. This situation presents an ideal target to vandals who break into the lock box, operate the push button and open the hopper doors through the use of the residual air pressure blocked in the reservoir tanks by check valves. While the air pressure of each reservoir tank could be drained to prevent the unauthorized operation of the hopper doors, such measures would be impractical as each reservoir would have to be pumped up on each reconnection to the locomotive, and the energy and time wasted over a period of time because of repeated pumpings would be significant.
From the foregoing, it is an object of the present invention to prevent the unauthorized unloading of fluid-activated hopper cars, without draining the fluid reservoir tank when such cars are disconnected from the primary source of air pressure, i.e., the locomotive.
It is a further object of the invention to prevent either the opening or the closing of the hopper doors for safety purposes, unless the locomotive is connected. In this manner, persons in and about an empty hopper car cannot be injured by a hopper door closing due to the operation of the manual push button.
Other objects and advantages will become apparent from the following description, taken in conjunction with the accompanying drawings.